矿物药炉甘石煅制前后锌、铅元素的赋存形态及分布特征研究

采用X射线衍射(XRD)技术和电子探针微区分析(EPMA)技术针对中药炉甘石煅制前后锌、铅元素的赋存形态及分布特征进行了研究，探明了煅制对炉甘石中锌、铅元素赋存状态及分布的改变，为后续水飞减除铅元素的机理研究提供了理论依据。测试结果显示：21批次炉甘石(生品)中的锌元素以主矿物水锌矿[Zn₅(CO₃)₂(OH)₆]和杂质矿物异极矿[Zn₄(OH)₂(H₂O)(Si₂O₇)]为主要赋存形态，偶见菱锌矿(ZnCO₃)；炉甘石(生品)的背散射电子图谱及元素分布数据显示：Zn和Pb元素同时分布的区域为水锌矿，Zn和Si元素同时分布的区域为异极矿，Ca和Mg元素同时分布的区域为白云石，Ca元素单独分布区域为方解石。在炉甘石(生品)中，Pb主要分布于水锌矿中且分布相对均匀，Pb元素的分布与水锌矿中的Zn元素密切相关。大量水锌矿的微区点位的电子探针定量分析结果显示：各不同点位中的ZnO/PbO含量的比值趋于定值，Pb在水锌矿中呈统计式均匀分布，说明Pb在水锌矿中主要以类质同象混入物的形式存在。但是炉甘石(生品)中的异极矿、方解石及白云石等杂质矿物中铅元素含量极低甚至检测不到。炉甘石煅烧后水锌矿晶格中的Zn和Pb分别生成了ZnO和PbO。Zn元素在炉甘石煅制品中主要以氧化锌(ZnO)形式存在，少部分以杂质矿物硅酸锌(Zn₂SiO₄)形式存在，呈较连续状态分布。Pb元素在炉甘石煅制品中主要以氧化铅(PbO)的形式存在，呈星点状分布，与Zn元素的分布未呈现相关性，说明Pb在炉甘石煅制品中是以独立矿物形式存在的。煅烧破坏了水锌矿的晶格结构，在改变锌、铅化合物形态的同时，更改变了锌、铅的分布特征，打破了炉甘石中锌、铅的共生状态，使水飞减除铅元素成为可能。

Study on the Occurrence Forms and Distribution Characteristics of Zinc and Lead Before and After Calcination of Mineral Medicine Calamine

Zinc element and lead element were gauged to reveal their occurrence forms and distribution characteristics inraw Calamine and calcined Calamine in order to get ready for the deducting of lead. X-ray diffraction (XRD) mothed was used to analyze the occurrence form, main carrier mineral of zinc and lead. Electron probe microanalysis (EPMA) methodwas usedto performregion-wide scanning of elements, qualitative and quantitative analysis of micro-area components of the raw and calcined Calamine. Stood on the XRD data of 21 batches samples, hydrozincite (Zn₅(CO₃)₂(OH)₆) was provedto be the main mineral species in raw Calamine, while smithsonite (ZnCO₃) was occasionally. As impurity minerals, hemimorphite (Zn₄(OH)₂(H₂O)(Si₂O₇), calcite (CaCO₃), dolomite (CaMg(CO₃)₂), quartz (SiO₂) were detected. For comparison with the raw Calamine, themain mineral of calcined Calaminewas zinc oxide (ZnO). The impurity minerals were zinc silicate (Zn₂SiO₄) and calcium Calcite (CaCO₃), while zinc ferrite (ZnFe₂O₄) was occasionally. Zinc is the subject element of Calamine. According to 21 batches of raw Calamine, Zn existed generally as the main mineral species as hydrozincite (Zn₅(CO₃)₂(OH)₆), and the impurity mineral speciesas hemimorphite (Zn₄(OH)₂(H₂O)(Si₂O₇), occasionally as smithsonite (ZnCO₃). The backscatter electron images and element distribution data from EPMA of raw Calamine samples illustrated that: Zn and Pb were simultaneously existent in hydrozincite area; Zn and Si were simultaneously existent in the hemimorphite area; Ca and Mg were simultaneously existent in the dolomite area; Ca was individually existent in the calcite area. In raw Calamine samples, Pb was mainly existent in hydrozincite area, closely associated with Zn element. Quantitative inspection of electron probes in a large number of hydrozincite sites showed that, the ratio of ZnO/PbO content in hydrozincite tended to be fixed, and Pb was statistically evenly distributed in hydrozincite, verifying that Pb occurs mainly in the lattice of hydrozincitein isomorphism. But Pb content was much lower in the area of hemimorphite, calcitenor dolomite of raw Calamine, even can’t be detected. Zn and Pb in the lattice of hydrozincite were respectively transformed into ZnO and PbO after calcination. Zinc distributed continuously in calcined Calamine, mainly existing in the form of zinc oxide and less of zinc silicate (Zn₂SiO₄). Lead distributedin isolation in calcined Calamine, mainly existing in the form of lead oxide, which no longer has correlation with zinc element. Calcination destroyed the lattice structure of hydrozincite, broke the symbiotic state of zinc and lead in Calamine, changed the distribution characteristics of the elements and enhanced the feasibility of deducting lead.